How do infants' developing phonological perception and awareness contribute to their ability to learn the meaning of words? In the proposed experiments, the preferential looking paradigm will be used to test if 1) 14-26-month-olds' word-object associations are phonetically detailed, and if so, 2) whether these infants actively suppress their awareness of these phonetic differences under specific circumstances. One set of studies will address infants' sensitivity to phonemic variability in pronunciations of words, while a second line of research looks at their sensitivity to small pronunciation differences (called allophonic differences) within different instances of the same word. This perspective of flexible word learning provides a new way of characterizing the process of lexical acquisition and challenges many long-held assumptions about the developing abilities of infants. In addition, the understanding this work provides for infants' flexibility in language learning situations is critical to the development of therapeutic interventions in the case of language delay or other developmental disorders and in helping normally developing children achieve more. [unreadable] [unreadable]